Field of the Invention
The present invention relates to a rebound suppression system for sliding door, and more particularly, to a rebound suppression system for sliding door capable of being easily incorporated into a machine without interfering with other components.
Description of the Related Art
A protective cover of a machine tool is provided with a sliding door that is opened and closed by a rail and rollers in order to externally access the interior. If the sliding door is swiftly opened or closed by an operator, it may sometimes rebound at an end of a movable part. FIG. 18 is a diagram showing an example of the structure of a conventional sliding door.
In the structure example shown in FIG. 18, a sliding door 1 is provided with a plurality of rollers 2, and a rail 4 is secured to its outer frame. As the rollers 2 rotate along the rail 4, the sliding door 1 moves in the direction indicated by M in FIG. 18.
When the sliding door 1 is housed in a door pocket 5, an operator can access the interior from outside the protective cover. Moreover, if the operator moves the sliding door 1 in the direction indicated by N in FIG. 18 to perform machining, a key 3 attached to the sliding door 1 is inserted into a lock mechanism 7 attached to a door frame 6 and locked by the lock mechanism 7, whereby a closed state of the sliding door 1 is maintained.
If the sliding door 1 is then swiftly moved toward the door frame 6 (in the direction indicated by N in FIG. 18), it may sometimes collide swiftly with the door frame 6 and rebound. If the sliding door 1 thus rebounds, a force generated by the rebound of the sliding door 1 is concentrated on the key 3 and the lock mechanism 7, as shown in FIG. 19. Therefore, the lock mechanism 7 is heavily loaded, so that it may be worn or broken. Thus, there is a demand for the suppression of such a rebound.
Moreover, so-called “rattling of a sliding door” may sometimes be caused such that the sliding door 1 cannot move to the innermost part of the door pocket at its open end when it is moved to its open or closed end or the sliding door 1 is not in contact with a fiddle at its closed end, as shown in FIG. 19. If such rattling of a sliding door is caused, a problem occurs that mist and chips leak out of the protective cover through a gap between the sliding door 1 and the fiddle at the closed end, in particular.
In some cases, furthermore, the machine tool is used in a severe environment where a cutting fluid, mist, chips and the like scatter. Therefore, there is a demand for a reduction in causes of failure based on the simplest possible structure of a system for suppressing rebound of a sliding door, and in addition, on the location of the rebound suppression system isolated from the interior of a machining chamber of the machine tool and the outside of the machine tool. On the other hand, various components such as a sensor, actuator, and conducting member are often mounted in positions isolated from the interior of the machining chamber of the machine tool and the outside of the machine tool, so that interference must be avoided. To attain this, the rebound suppression system for sliding door is expected to be small-sized and design flexibility is required of the installation location.
For example, Japanese Patent Application Laid-Open No. 2006-219885 discloses, as a means for overcoming the rebound of a sliding door, a roller latch mechanism that is configured to press a roller against a tapered surface of a roller guide, thereby preventing the sliding door from rebounding.
In the technique disclosed in Japanese Patent Application Laid-Open No. 2006-219885 described above, however, the rebound of the sliding door is prevented by providing a structure such that the roller that is continually pushed up by a spring is attached to the upper part of the door end and is pressed against the tapered surface of the roller guide in the vicinity of a position in which the sliding door is closed.
In many of machine tools, however, a safety switch and other sensors, actuator and the like are attached to the upper part of the door end of the sliding door, and interference with those components sometimes cannot be avoided due to design limitation. Even when the roller is located in a position other than the door end of the sliding door, the roller guide must be disposed based on the movable range of the sliding door, so that the problem of the interference with the other components can be completely avoided.